Premature capacity loss, an overlooked phenomenon in telecom batteries

Premature capacity loss (PCL) has been known in the field of lead-acid batteries for cyclic applications for a long time. Little is described about its occurrence in telecommunication applications. PCL is used to describe a rather abrupt capacity degradation that occurs without apparent physical effects inside the battery. PCL is apparent during the discharge where the voltage suddenly drops and can go down to very low values early in the discharge; however the cells will not reverse. PCL is not due to dry-out or undercharging. Cells affected with PCL will not recover: (a) when treated with equalization charge; or (b) when treated with additional water. However PCL cells will recover when treated with a reconditioning discharge. This paper exemplifies this with some data from the author´s in-house reference batteries. The paper also transfers some general findings from other fields of lead-acid battery science where this phenomenon has been studied in more detail. It is the conclusion of the author that PCL is best treated by changing the design of the batteries themselves